UPSC CGGE 2017 Question Paper Chemistry Paper II

GEOLOGIST EXAM-2017
ZLX-D-CHE

CHEMISTRY

Paper— II

Time Allowed : Three Hours Maximum Marks : 200

QUESTION PAPER SPECIFIC INSTRUCTIONS

Please read each o f the following instructions carefully
before attempting questions

There are FIFTEEN questions divided under THREE Sections.

Candidate has to attempt TEN questions in all.

The ONLY question in Section A is compulsory.

In Section B. SIX out o f NINE questions arc to be attempted.

In Scction C, THREE out o f FIVE questions are to be attempted.

The number o f marks carried by a question/part is indicated against it.

Attempts o f questions shall be counted in sequential order. Unless struck off. attempt o f a
question shall be countcd even if attempted partly.

Neat sketches are to be drawn to illustrate answers, wherever required.

Unless otherwise mentioned, symbols and notations have their usual standard meanings.

Assume suitable data, i f neccssary and indicate the same clceirly.

Any page or portion o f the page left blank in the QCA Booklet must be clearly struck off.

Answers must be written in ENGLISH only.

1 ( p.T.O.

Some usehil fundamentai coattants and conversion factors

JVa • 6 -022 x 10 “ m or*

Rydberg constant " 2*178xl0"*® J

c = 2 998x10® m s ‘

/Cb - l-3 8 x lO "“ J K“*

e - 1-602x10**^ C

- 9-109x10"^* kg

F - 96485 C m o r ‘

R - 8-314 J K~‘ m o r ’

h - 6-626 xlQ-^'* J b

n - 3-142

1 amu “ 1-66x10"^

1 cal = 4-184 J

1 J “ 1 kg s"^

1 A - I 0 ~® cm - 10"*® m “ 0-1 nm " 100 pm

I atm * 760 torr = l'0 1 3 2 5 xl0 ® Pa

1 bar - 1x10® Pa - 0-9869 atm

1 eV - 1-602X10'*® J

1 L atjn « 101-34 J

S ec tio n —A

1. Answer all o f ihe following : 30

(a) Write down the equation of state for van der Waals gases with symbolic
significances and And the dimension o f van dcr Waals constants. 8

(b) Helium gas at 500 K expands adiabatically and reversibly to double its volume.
Find the final temperature of the gas in degree Celsius. (Assume that He gas
behaves ideally.) 6

(c) Explain the Arrhenius theory o f acids and bases with examples.

(df List the factors which influence the efficiency of Camot engine. How?

(e) The effect o f temperature on the value of dimerization constant is negative.
Justify with the help of van*t Hoff equation isobar. 6

(/) Derive the integrated rate equation for a zero-order reaction. Give one example
of zero-order reaction. 6

fg) What is van’t Hoff factor (i) of a solution? Derive its relation with degree of
ionization of solute in a solution. 6

fh) Define Vnolar extinction coefficient (e)’. What is its unit? What factor(s) can
influence its value? 6

(i) Show that the unit o f magnetic dipole moment is A m^ which is also equivalent
to J T Here T stands for tesla, the unit o f magnetic field strength.

(j) Why is surface tension o f liquid ethanol greater than liquid dimethyl ether
though both have same molecular mass? 5

3 ( p.T.O.

(k) Explain why H 2O is a liquid while H^S is a gas at room temperature.

(I) Show that y - e'*** is an cigenfunction of the operator, A = What is the
dx
eigenvalue?

(m) Which of the following transitions are allowed in the normal electronic emission
spectrum o f an atom? Give reason(s) ; 8

(i) 2 s - » I s

(U) 2 p - » l s

(mi 3 d -> 2 p

(iv) 3d -♦ 4s

(v) 5 p - » 3 s

S e c t io n — B

Attempt <ani/ six questions ; 10x6-60

( dV\
2. Derive (C p -C y ,)* +P — (symbols have their usual meanmgs).
.3V, r.n ^T'^P.n
Find the expression of (Cp - Cy) for a gas obeying equation of state, = n/?T. 10

3. 18*0 g of liquid water vaporizes at 1 bar and 373 K. Calculate q, w, &,V, &S,
and AC (in SI units) for this process. Given, latent heat of vaporization of liquid
water at 1 bar and 373 K is 540 caJg ^ 10

4. Derive Gibbs-Duhem equations for a mixture system at constant pressure and
temperature. 10

5. O 'lk g m o l'* aqueous solutions o f two 1-1 electrolytes A and B freeze at
- 0‘360 ‘ C and - 0-208 "C. respectively. Calculate (a) van*! liofT factor o f each
solution and (b) the degrees of ionization of A and B in their solution. Suggest the
nature of electrolytes. Given, Ky o f water • 1-86 K kg m ol"’ . Iq

6. (a) What will be the value of absorbance of transparent liquid water with respect to
visible light? Give reason.

(b) Write a note on ‘photosensitized reaction’ with example of photosynthesis.
2 +8=10

7. (a) Define 'most probable speed' of a molecule in gaseous system, Derive its
expression using the following speed distribution equation :

3/2 mc3
m
c^e dc
2nkQT

(Symbols have their usual meanings.)

(b) Find the pH of 10"'’ (Af) aqueous caustic soda solution. 8+2-10

8 . (a) Show that for a first-order reaction, the time required for completion of 99-9%
reaction is ten times of its half-life period.

(b) The standard reduction potential value of Zn * * /2n electrode is negative and of
Cu**/Cu electrode is positive. What vnll be the cell reaction, if we couple two
electrodes to form a galvanic cell? Give reason|s) in support o f your answer.
S+5-10

9. A spherical water drop of radius 1 0 mm is sprayed into a million o f droplets of same
size. Find the work done in this process. Given that y (surface tension) o f water at
the experimental temperature is 72*0 dyne cm"*. 10

5 ( P.T.O.

10. (a) Silver crystaUizes in an f.c.c. structtire with a unit ccU length o f 408-6 pra.
Using Bragg equation, calculate the flrst-order difTraction angle Tor (U 1) plane
using X-ray of wavelength 154-433 pm.

(b) The forcc constant of a harmonic oscillator of reduccd mass l-5 x l0 '^ ^ kg is
10 N m ‘ *. Calculate its zcro*point energy. 5+5-10

S e c t io n — C

Attempt any three questions ; 20x3-60

11. (a) Derive - K j m 2 (symbols have their usual meanings} using thermodynamic
concept o f chemical potential. Mention all assumptions and approximations at
proper places.

(b) The temperature of a hot cup of tea decreases spontaneously in a closcd
^ stem at constant pressure without loosing its mass. So for this change
<0. ASuniv > 0 A 0 > 0 . Justify with reasons. 10-*-10=20

12. (a) Discuss hypochromic effect in connetion to UV spectra.

fb) The quantum yield (<» for the reaction, 2HI H j + 13, at X » 250 nm is 2-0. If
3070 J of light is absorbed, find the number o f moles of HI decomposed.

(c} What is indicated by peak area in PMR spectrum? How many peaks will be
observed in PMR spectrum of pure ethanol? What will be their peak area ratio?
Explain with diagram, if possible. 5+5-''10-20

13. (a) Write down Debye-Hiiickel limiting equation with symbolic significances and
units. Find the ionic strength of 0-01 molL*’ aqueous solution of potassium
ferrocyanide.

(b) The average lifetime of phosphoresccnce is higher than fluorescence. Explain
with JablonslQ^ diagram.

(cf Hydrogen nucleus is NMR active but the nuclei of and arc inactive.
Explain why. l0+5-*-5®20

14. (a) Derive Langmuir adsorption isothenn expression for the proccss

03 fe)-4 3O(ads)

Calculate the equilibrium constant, K for this process when the coverage of
O (ads) is 0 50 at - 1 atm.

(b) The wave number o f J « ' O t o J » l transition for pure rotational spectrum of
is 16-93 cm~*. Assuming the molecule as a rigid rotor, calculate its
moment of inertia in k g m^ and equilibrium bond length in m. 10 + 10*20

15. (a) Derive the expressions of critical constants [P^, and 7^) for van dor Waals
gases.

(b) {n an aqueous solution of HCl, the transport number of ion is abnormally
higher than Cl* ion. Explain why.

(c) Find the units o f A and (in SI units) using the equation, .
k is the zero-order rate constant. 8+8+4**20

$g5£^S 6-‘«9<^/77 7 7BS— 11695